There are several processes for performing combination printing of flat surfaces, involving multiple layers of print. The underlying print layers are usually cured or hardened by radiation, chemical treatment, or heat before top layers are added.
As an example, U.S. Pat. No. 6,443,058 to Stadler, et al. teaches a process combining two ink systems. The underlying substrate is first printed with a solvent-based or radiation-cured ink and then with at least one offset-typical ink. The patent teaches inline implementation via a hybrid press, having a flexo printing unit and a downstream offset printing unit. A UV, electron-beam or air-stream dryer is also integrated into the flexo printing unit, or, alternatively, a UV, electron-beam or air-stream drying unit is used.
Specifically for pad printing of curved or irregular surfaces, a new process is required to combine the advantages of pad printing with the hybrid process concept.